This application claims the priority of International Application No. PCT/DE2007/000283, filed Feb. 15, 2007, and German Patent Document No. 10 2006 008 210.9, filed Feb. 22, 2006, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a peening chamber for surface peening, in particular for ultrasonic shot peening of gas turbine components.
Such a peening chamber has already been known from document U.S. Pat. No. 6,490,899 B2, whereby, in the chamber, the tops of a plurality of turbine blades of a turbojet engine can be simultaneously surface-treated by peening.
By using such shot peening, it is possible, for example by abrasion or the like, to harden heavily stressed components and component sections of gas turbines. Likewise, by using this special surface-treatment process, it is possible to minimize, or at most eliminate, distortions, material movements or other defects, for example on the edges of rotors or in blade areas. Finally, shot peening can be used to post-treat gaps at joints of repaired turbine blades or similar components.
Referring to the known peening chamber, the plurality of turbine blades are to be positioned head first inside an accommodation frame in such a manner that their blade tips comprising the surface to be treated project through an associate wall orifice inside the frame. In so doing, the frame itself forms a horizontally extending upper wall region of the peening chamber, the wall region being located opposite and parallel to a sonotrode's vibrating plate extending in a horizontal direction and forming the lower wall region of the peening chamber. In so doing, the frame is to be fixed in place in an associate frame opening in such a manner that the blade tips comprising the surfaces to be treated are located inside the peening chamber. Now, by using the sonotrode that has been excited by ultrasonic vibrations, a bead cloud can be generated inside the peening chamber, the bead cloud being used for the surface treatment of the blade tips of the turbine blades.
Furthermore, German Patent Document No. DE 10 2004 029 546 A1 has disclosed a peening chamber, in which a blade root of a gas turbine blade can be treated by means of an ultrasonic shot peening process. To do so, a passage opening is provided inside a vertically extending wall region of the peening chamber, in which case the gas turbine blade is to be pushed through the passage opening. A horizontally extending lower wall region of the overall essentially cube-shaped peening chamber is formed by a surface of a sonotrode that is to be excited by ultrasonic vibrations. As a result of this, the steel beads arranged inside the peening chamber are accelerated for the treatment of the blade root.
The disadvantage of each of these known peening chambers must be considered to be the circumstance that they are adapted quite specifically to one situation of application or to the treatment of a specific component. Consequently, the geometric configuration of the peening chambers is adapted to the component to be treated or to the component area to be treated in such a manner that a desired quality of the treated surface can be achieved. In addition, wall openings are provided in the respective wall region of the chamber wall or of the accommodation frame, the openings being specifically adapted to the cross-section of the component to be treated.
Therefore, it is the object of the present invention to improve a peening chamber of the aforementioned type in such a manner that the chamber can be adapted, with minimal expense and effort, to various components that are to be treated.
Referring to the peening chamber in accordance with the invention, at least one wall region of the chamber wall is designed so that it can be adjusted in order to change the geometric configuration of the chamber. In other words: the invention is based on the basic idea that the geometric configuration—namely, for example, the size and/or shape—of the peening chamber can be adapted or adjusted to the component to be treated, in that at least one wall region of the chamber wall is designed so as to be adjustable. As a result of this, it is not only possible to adapt or adjust the peening chamber to the different sizes of the components to be treated, but, rather—as a result of appropriate adjustments of the at least one wall region of the chamber wall—it is also possible, for example, to influence the distances and angles, at which the peening agent—for example, the beads in ultrasonic shot peening—will be deflected.
In the end, it is thus possible to produce a universally usable peening chamber that can be automatically adapted or adjusted—with extremely minimal expense and effort for setup—to various contours or components. Consequently, it is possible, in a simple manner, to treat components having different shapes and sizes inside one and the same peening chamber.
To accomplish this, the wall regions of the chamber wall that are to be adjusted can be slid in a linear direction, their angles may be adjusted, or they may be changed creating a different free form area, depending on the geometric configuration of the peening chamber that is optimal for the respectively to be treated component.
Referring to another embodiment of the invention, in particular one adjustment of the geometric configuration of the peening chamber has been found to be particularly easy to implement, i.e., in that at least one wall region of the chamber wall can be changed by being inflated. Consequently, it is possible to change the contour of the appropriate chamber wall by simply introducing or evacuating a gaseous medium. In so doing, it is conceivable, for example, to design the wall region or the chamber wall itself as an inflatable cushion. Likewise, it would also be conceivable to support the adjustable wall region with an inflatable cushion, thus permitting an appropriate adjustment of the wall region. Instead of a gaseous medium, it would also be conceivable, of course, to adjust the variable wall region of the chamber wall, for example, with the use of a liquid medium such as oil or the like.
Referring to another embodiment of the invention, it is further conceivable to design the chamber wall of the peening chamber of a flexible, elastic material and, in particular, of a rubber material. The side facing the component region must be appropriately sturdy on the chamber wall in order to be able to withstand, for example, the stress due to the beads used in ultrasonic shot peening. Furthermore, the chamber wall must also be stiff, so that, for example, the beads are deflected by the chamber wall in the desired manner. In conjunction with this, it is possible, for example, to provide the chamber wall—on its side facing the component region to be treated—with a cover or sheeting or the like, i.e., at least locally.
In order to be able to treat various components with the use of a single peening chamber, whereby only one component region comprising the surface to be treated is arranged inside the chamber wall or the peening chamber, it has been found to be particularly favorable—considering a further embodiment of the invention—to design the wall region of the chamber wall adjacent to the wall opening so as to be adjustable. In other words: it is also possible to provide the adjustable wall region of the chamber wall in accordance with the invention only in the region of the wall opening, through which the component region comprising the surface to be treated is passed. In conjunction with this, it is conceivable that only a part of the wall region surrounding the wall opening or also the entire peripheral wall region can be adjusted. Thus, in the end, the wall opening can be adjusted and adapted, in a simple manner, to varying sizes and geometric configurations of different components that are to be treated. As a result of this, it is not only possible to achieve a universally useable peening chamber but, beyond that, it is possible to reduce to a minimum the setup times used for the adjustment to a different component geometry.
In order to prevent peening agent from escaping between the wall opening and the component inserted therein, it has been found to be advantageous in a further embodiment of the invention to design the wall region of the chamber wall adjoining the wall opening as a seal. In addition to avoiding a loss of peening agent, it can thus be achieved that the surface that is to be treated can be precisely defined, or the component region to be treated can be separated extremely precisely from the component region that is not to be treated.
If, beyond that, a sliding element is provided in the contact region of the seal at the site where the component is passed through the wall opening, it is possible—in a simple manner—to move, for example rotate, the component inside the peening chamber during surface peening in order to achieve the best possible surface of the component.
In order to achieve a particularly good surface result, in particular with shot peening, it has further been found to be advantageous to provide or arrange an ultrasonic sonotrode, in particular inside the peening chamber. Referring to a particularly preferred embodiment, the surface of the sonotrode forms a wall region of the chamber wall.
Referring to the preferred embodiment, the at least one wall region that can be adjusted in order to change the geometric configuration of the peening chamber is different from the ultrasonic sonotrode, that is, in particular, also when one surface of the sonotrode forms a wall region of the chamber wall.
If a device for the detection of a sound emission of the peening agent is provided inside the peening chamber, the loss of peening agent—due to the concomitant change of the sound emission—can be detected in a simple manner in this way.
Furthermore, it has also been found to be advantageous if the peening chamber is associated with a device for metered replenishing of the peening agent present inside the peening chamber. As a result of this, it is possible to keep the amount of peening agent inside the peening chamber constant and to achieve, accordingly, a reproducible and highly consistent peening result.
Finally, a particularly advantageous peening chamber can be achieved in that the device for metered replenishing is connected to the device for detecting the sound emission of the peening material. If, in accordance with this, a loss of peening agent is detected by means of the device for the detection of a sound emission, this loss can easily be compensated for by the device for metered replenishing in order to ensure a uniform and reproducible peening result.
Additional advantages, features and details of the invention are provided from the following description of a preferred exemplary embodiment and from the drawings.